What is a (Volvox) species?

Hisayoshi Nozaki and colleagues have just described some Volvox samples from two lakes and a pond in Japan.

Figure 1A from Nozaki et al. 2016. Volvox sp. Sagami asexual spheroid with daughter colonies (d).

Figure 1A from Nozaki et al. 2016. Volvox sp. Sagami asexual spheroid with daughter colonies (d).

The newly collected strains have a lot in common with another recently described species, Volvox ferrisii, but there are some important differences as well:

…it could be clearly distinguished from all previously described monoecious species of Volvox sect. Volvox by its small number of eggs or zygotes (5–25) in sexual spheroids, with short acute spines (up to 3 μm long) on the zygote walls and elongated anterior somatic cells in asexual spheroids.

In spite of these differences, Nozaki and colleagues stop short of calling the newly collected strains a new species. Why?

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Volvox 2015: development

Replica of Antonie van Leeuwenhoek's microscope.

Ray Goldstein‘s working (!) replica of Antonie van Leeuwenhoek’s microscope.

At the start of the Development session, I asked for a show of hands of people who self-identify as developmental biologists. About four went up. That’s not quite fair, since there’s some ambiguity in the question (primarily? exclusively?), but my point was that what all of us who are interested in the evolution of multicellularity study is the evolution of development. In fact, it might fairly be said that the origin of multicellularity is the origin of development.

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African Volvox in Montana

Ninepipe Reservoir

Ninepipe Reservoir near Charlo, MT. Photo by Aeravi.

Last summer, I hosted Drs. Hisayoshi Nozaki, Noriko Ueki, Osami Misumi, and two graduate students from the University of Tokyo, Kayoko Yamamoto and Shota Yamashita, to collect volvocine algae from Montana lakes. To our surprise, we found a species of Volvox (V. capensis) that had previously only ever been found in South Africa! Dr. Nozaki’s team identified the algae collected in Ninepipe Reservoir based on their morphology and DNA sequencing. South Africa and Montana: this is about as disjunct as a distribution can be. Is Volvox capensis a master of long-distance dispersal? Is its distribution actually cosmopolitan, and if so, why hasn’t it ever been found anywhere else?

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